The present application is a U.S. national application of PCT/IL98/00521, filed Oct. 26, 1998.
The invention relates to motors for providing motion to a moveable element and in particular to providing motion of a moveable element in more than one direction using motors, for example, piezoelectric motors.
Piezoelectric motors use vibrators made of piezoelectric materials to convert electrical energy into mechanical motion. The motors are used in many and varied applications and have been designed to impart motion to moveable elements in, among other things, automotive fuel injectors, videocassette recorders, automatic cameras, computer disc drives, and precision microscope stages.
Most piezoelectric motors generally impart motion to moveable elements to which they are coupled back and forth along a single straight line, hereinafter referred to as an xe2x80x9caxis of motionxe2x80x9d. To impart motion to a moveable element along more than one axis of motion, generally a different piezoelectric motor is coupled to the moveable element for each different axis of motion desired.
Modem devices often comprise many small intricate parts that move with different forms of motion and in many different directions with respect to each other. These devices often have limited room available for a plurality of motors to effect these motions. It would be advantageous to have a piezoelectric motor that can by itself impart motion to a moveable element to which it is coupled along different axes of motion.
Aspects of preferred embodiments of the present invention relate to providing a piezoelectric motor, hereinafter referred to as a xe2x80x9cmultidirectional motorxe2x80x9d, that can impart motion to a moveable element along a plurality of axes of motion.
In a preferred embodiment of the present invention a multidirectional motor comprises first and second piezoelectric motors. The first motor, hereinafter referred to as a xe2x80x9cdriving motorxe2x80x9d, is coupled to a moveable element and imparts motion to the moveable element back and forth along an axis of motion. The direction of the axis of motion is determined by the orientation of the driving motor with respect to the moveable element. The second motor, hereinafter referred to as a xe2x80x9csteering motorxe2x80x9d, is coupled to the first motor. Activation of the steering motor changes the orientation of the first motor with respect to the moveable element and thereby the axis of motion along which the first motor imparts motion to the moveable element.
Whereas the driving motor and the steering motor are described as being piezoelectric motors it should be realized that the steering motor can be any suitable motor or actuator, such for example an electromagnetic motor, a gas driven motor or a solenoid, appropriately coupled to control the orientation of the driving motor. Furthermore, the driving motor can be any motor that is friction coupled to the moveable element so as to impart motion to the moveable element.
There is therefore provided in accordance with a preferred embodiment of the present invention a multidirectional motor system for transmitting motion to a moveable element in at least two directions that are not collinear, comprising: a first motor that is coupled to the moveable element and transmits motion to the moveable element along a direction determined by the orientation of the first motor; a second motor operable to change the orientation of the first motor. Preferably, the first motor is friction coupled to the moveable element and presses on a surface region of the moveable element.
Preferably, the second motor is operable to rotate the first motor around an axis through a point on the surface region of the moveable element on which the first motor presses.
Preferably, the multidirectional motor system comprises a frame in which the first motor is mounted and the second motor is operable to rotate the frame about the axis, which frame comprises at least one support that prevents the first motor from rotating with respect to the frame about the axis.
The frame preferably comprises a circularly cylindrical surface having an axis of revolution that coincides substantially with the axis and wherein the second motor presses on the cylindrical surface and is operable to rotate the cylindrical surface.
In some preferred embodiments of the present invention the cylindrical surface has an azimuthal extent about the axis of rotation that is substantially equal to 180xc2x0. In some preferred embodiments of the present invention, the cylindrical surface has an azimuthal extent substantially equal to 360xc2x0.
In some preferred embodiments of the present invention the at least one support is connected to the cylindrical surface.
In some preferred embodiments of the present invention the frame comprises a planar mounting plate having two parallel planar surfaces that are perpendicular to the axis of rotation and the cylindrical surface is fixed to a planar surface on one side of the mounting plate and the first motor is fixed to the frame on the other side of the mounting plate. In some preferred embodiments of the present invention the cylindrical surface is convex. In other preferred embodiments of the present invention the cylindrical surface is concave.
In some preferred embodiments of the present invention the frame comprises a planar mounting plate having two parallel planar surfaces, the axis passes through the mounting plate and is perpendicular to the planar surfaces and the second motor presses on one of the planar surfaces and is operable to rotate the mounting plate around the axis.
Additionally or alternatively, the first motor comprises a piezoelectric motor. Additionally or alternatively, the second motor comprises a piezoelectric motor.
There is further provided in accordance with a preferred embodiment of the present invention a method of transmitting motion to a moveable element along a plurality of directions comprising: friction coupling a first motor to the moveable element by pressing a first motor to a surface region of the moveable element, which first motor transmits motion to the moveable element along a direction that is determined by the orientation the first motor; and changing the orientation of the first motor.
Preferably, changing the orientation of the first motor comprises using a second motor to change the orientation of the first motor. Using the second motor preferably comprises using the second motor to rotate the first motor about an axis substantially perpendicular to the surface region.
Additionally or alternatively, the first motor is a piezoelectric motor. Additionally or alternatively, the second motor is a piezoelectric motor.
The invention will be more clearly understood by reference to the following description of preferred embodiments thereof read in conjunction with the figures attached hereto. In the figures identical structures, elements or parts which appear in more than one figure are labeled with the same numeral in all the figures in which they appear.